for an increase in voltage IN THE SAME SYSTEM you use ohm's law. I= V/R
As voltage increases with resistance remaning the same, amps increase.
a 24 volt system vs 12 volt system the resistance isn't the same.
it would have to be twice that of a 12 volt system to require half the amps.
they decide on 12 volt vs 24 volts based on watts used amps times voltage. so if for instance a starter requires 480 watts at 12 volts you would pull 40 amps but a 24 volt system pulling 480 watts would only need 20 amps.
but the physical starter would be wired differently increasing the resistance.
